docs: def list_set(self, key, index, value, **kwargs):
          """
          Sets an item within a list at a given position.
  
          :param key: The key of the document
          :param index: The position to replace
          :param value: The value to be inserted
          :param kwargs: Additional arguments to :meth:`mutate_in`
          :return: :class:`OperationResult`
          :raise: :cb_exc:`NotFoundError` if the list does not exist
          :raise: :exc:`IndexError` if the index is out of bounds
  
          example::
  
              cb.upsert('a_list', ['hello', 'world'])
              cb.list_set('a_list', 1, 'good')
              cb.get('a_list').value # => ['hello', 'good']
  
          .. seealso:: :meth:`map_add`, :meth:`list_append`
          """
          op = SD.replace('[{0}]'.format(index), value)
          sdres = self.mutate_in(key, op, **kwargs)
          return self._wrap_dsop(sdres)